tests: Add a test for device hot unplug

There is a test which verifies unloading of i915 driver module but no
test exists that checks how a driver behaves when it gets unbound from
a device or when the device gets unplugged.  Implement such test using
sysfs interface.

Two minimalistic subtests - "unbind-rebind" and "unplug-rescan" -
perform the named operations on a DRM device which is believed to be
not in use.  Another pair of subtests named "hotunbind-lateclose" and
hotunplug-lateclose" do the same on a DRM device while keeping its file
descriptor open and close it thereafter.

v2: Run a subprocess with dummy_load instead of external command
    (Antonio).
v3: Run dummy_load from the test process directly (Antonio).
v4: Run dummy_load from inside subtests (Antonio).
v5: Try to restore the device to a working state after each subtest
    (Petri, Daniel).
v6: Run workload inside an igt helper subprocess so resources consumed
    by the workload are cleaned up automatically on workload subprocess
    crash, without affecting test results,
  - move the igt helper with workload back from subtests to initial
    fixture so workload crash also does not affect test results,
  - other cleanups suggested by Katarzyna and Chris.
v7: No changes.
v8: Move workload functions back from fixture to subtests,
  - register different actions and different workloads in respective
    tables and iterate over those tables while enumerating subtests,
  - introduce new subtest flavors by simply omitting module unload step,
  - instead of simply requesting bus rescan or not, introduce action
    specific device recovery helpers, required specifically with those
    new subtests not touching the module,
  - split workload functions in two parts, one spawning the workload,
    the other waiting for its completion,
  - for the new subtests not requiring module unload, run workload
    functions directly from the test process and use new workload
    completion wait functions in place of subprocess completion wait,
  - take more control over logging, longjumps and exit codes in
    workload subprocesses,
  - add some debug messages for easy progress watching,
  - move function API descriptions on top of respective typedefs.
v9: All changes after Daniel's comments - thanks!
  - flatten the code, don't try to create a midlayer (Daniel),
  - provide minimal subtests that even don't keep device open (Daniel),
  - don't use driver unbind in more advanced subtests (Daniel),
  - provide subtests with different level of resources allocated
    during device unplug (Daniel),
  - provide subtests which check driver behavior after device hot
    unplug (Daniel).
v10 Rename variables and function arguments to something that
    indicates they're file descriptors (Daniel),
  - introduce a data structure that contains various file descriptors
    and a helper function to set them all (Daniel),
  - fix strange indentation (Daniel),
  - limit scope to first three subtests as the initial set of tests to
    merge (Daniel).
v11 Fix typos in some comments,
  - use SPDX license identifier,
  - include a per-patch changelog in the commit message (Daniel).
v12 We don't use SPDX license identifiers nor GPL-2.0 in IGT (Petri),
  - avoid chipset, make sure we reopen the same device (Chris),
  - rename subtest "drm_open-hotunplug" to "hotunplug-lateclose",
  - add subtest "hotunbind-lateclose" (less affected by IOMMU issues),
  - move some redundant code to helpers,
  - reorder some helpers,
  - reword some messages and comments,
  - clean up headers.
v13 Add test / subtest descriptions (patchwork).
v14 Extract redundant device rescan and reopen code to a 'healthcheck'
    helper,
  - call igt_abort_on_f() on device reopen failure (Petri),
  - if any timeout set with igt_set_timeout() inside a subtest expires,
    call igt_abort_on_f() from a follow-up igt_fixture (Petri),
  - when running on a i915 device, require GEM and call
    igt_abort_on_f() if no usable GEM is detected on device reopen.
v15 Add the test to CI blacklist (Martin).
v16 Separate blacklist entry with a descriptive comment (Petri).

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@intel.com>
Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Katarzyna Dec <katarzyna.dec@intel.com>
Cc: Martin Peres <martin.peres@linux.intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Petri Latvala <petri.latvala@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/tests/intel-ci/blacklist.txt b/tests/intel-ci/blacklist.txt
index ee7045f0..08333aff 100644
--- a/tests/intel-ci/blacklist.txt
+++ b/tests/intel-ci/blacklist.txt
@@ -117,3 +117,7 @@ igt@.*@.*pipe-f($|-.*)
 # Since 5.7-rc1, this test has produced tens of megabytes of kernel
 # logs.
 igt@perf_pmu@cpu-hotplug
+
+# Currently fails and leaves the machine in a very bad state, and
+# causes coverage loss for other tests.
+igt@core_hotunplug@.*